Read more of Daniel Engber's columns on obesity and health care reform.
In my last column ("Let Them Drink Water!"), I suggested that a tax on sweetened soft drinks would move the nation toward an apartheid of pleasure in which the poor must drink from the faucet while the rich enjoy superpremium fruit juice. I also argued that the soda tax discriminates on economic grounds, since rates of soft drink consumption tend to be highest in poor, nonwhite communities. But supporters of the measure counter that these very communities would benefit most from drinking less soda and that revenue from a regressive fat tax could be spent on laudable progressive goals—like universal health care.
The relationship between poverty and obesity keeps turning up in the debate over health care reform. Among the 46 million people in America who lack medical insurance, about two-thirds earn less than twice the poverty level (PDF). Advocates for universal coverage say that we can pay for all these new patients by cutting back on obesity rates, since excess fat accounts for 9 percent of the country's spending on medical care. (During the campaign, then-Sen. Obama claimed this might save the Medicare system $1 trillion.) Some even suggest that a reform package should include special taxes or higher premiums for fat people. That idea starts to seem misguided, though, when you consider that poverty and obesity tend to overlap in some complicated ways.
As a matter of public health, it might be more important to help poor people than fat people. According to epidemiologist Peter Muennig, the relative risk of mortality for being obese is between 1 and 2. That means that, controlling for other factors, someone who's really fat is up to twice as likely to die early as someone whose body mass index is in the normal range. But if you compare people from the top and bottom of the wage scale (with everything else held constant), the risk ratio goes up to about 3.5. In other words, it's much better for your health to be rich and fat than poor and thin.
Those in greatest need, furthermore, tend to be both poor and fat. We know, for instance, that the lower your income, the more likely you are to inhabit an "obesogenic" environment. Food options in poor neighborhoods are severely limited: It's a lot easier to find quarter waters and pork rinds on the corner than fresh fruit and vegetables. Low-income workers may also have less time to cook their own meals, less money to join sports clubs, and less opportunity to exercise outdoors.
If poverty can be fattening, so, too, can fat be impoverishing. Paul Ernsberger, a professor of nutrition at Case Western Reserve University, lays out this argument in an essay from The Fat Studies Reader, due out in November. Women who are two standard deviations overweight (that's 64 pounds above normal) make 9 percent less money (PDF), which equates to having 1.5 fewer years of education or three fewer years of work experience. Obese women are also half as likely to attend college as their peers (PDF) and 20 percent less likely to get married. (Marriage seems to help alleviate poverty.)
When it comes to public health, the relationship between poverty and obesity gets more convoluted. Being fat can make you poor, and being poor can make you sick, which means that being fat can make you sick irrespective of any weight-related diseases. Fatness (or the lifestyle associated with obesity) also creates its own health problems, regardless of how much money you have—and health problems tend to make people poor, through hospital bills and missed days of work. So fat can be impoverishing irrespective of any weight-related discrimination.
The point here is that sickness, poverty, and obesity are spun together in a dense web of reciprocal causality. Anyone who's fat is more likely to be poor and sick. Anyone who's poor is more likely to be fat and sick. And anyone who's sick is more likely to be poor and fat.
Sociologists describe these patterns in terms of social gradients. The "health-wealth gradient" refers to the fact that, as a general rule, the richer you are, the healthier you are. This applies across different countries and across the full range of social classes within the same country. (It's not just that the very poorest people are sick.) No one knows exactly what causes the health-wealth gradient or why it's so resilient. It may be that rich people have access to better health care. Or, as we've seen, it could be that being sick costs you money. Then there's the possibility that poor people have a greater incentive to behave in unhealthy ways: Since they don't have as much money to spend on happiness, they "spend" their health instead. (The pleasures of smoking and eating, for example, are easy on the wallet and hard on the body.)